Absorption spectra of organic molecules

Sandorfy, C. Electric Absorption Spectra of Organic Molecules Valence-Shell and Rydberg Transitions. 86,91-138 (1979). 

Labhart, H., Heinzelmann, W. Triplet-triplet absorption spectra of organic molecules. In Organic molecular photophysics. Vol. l,p.297. (ed. J. B. Birks). New York Wiley 1973. 

The effect is observed when the heavy atom is substituted in the molecule (intramolecular effect) as also when the molecule collides with a heavy atom containing perturber (intermolecular or external effect). The dramatic enhancement of S —T transition due to intramolecular and intermolecular heavy atom perturbations are respectively shown in Figure 3.8 for chloronaphthalenes in ethyl iodide and other perturbants. Molecular oxygen has a perturbing effect on S — T absorption spectra of organic molecules in solution. Under a pressure of 100 atm of Os, well defined... 

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